- Which of the following enzymes is used to reverse transcribe RNA into DNA?
a) DNA polymerase
b) Ligase
c) Reverse transcriptase
d) Restriction enzyme
Answer: c) Reverse transcriptase
Explanation:
Reverse transcriptase is an enzyme used to synthesize complementary DNA (cDNA) from an RNA template. This is especially useful in studying gene expression by converting mRNA into DNA for cloning or PCR.
- The enzyme responsible for cutting DNA at specific nucleotide sequences is:
a) DNA ligase
b) Helicase
c) Restriction endonuclease
d) RNA polymerase
Answer: c) Restriction endonuclease
Explanation:
Restriction endonucleases (restriction enzymes) cut DNA at specific recognition sequences, which is essential for manipulating and recombining DNA in genetic engineering.
- Which organism has been genetically modified to produce human growth hormone?
a) Escherichia coli
b) Saccharomyces cerevisiae
c) Rhizobium
d) Penicillium notatum
Answer: a) Escherichia coli
Explanation:
Escherichia coli has been genetically modified to produce human growth hormone (hGH) using recombinant DNA technology. The hGH gene is inserted into E. coli, which then expresses the hormone for therapeutic use.
- Which of the following crops has been genetically modified for herbicide resistance?
a) Bt cotton
b) Flavr Savr tomato
c) Roundup Ready soybean
d) Golden Rice
Answer: c) Roundup Ready soybean
Explanation:
Roundup Ready soybeans are genetically engineered to be resistant to the herbicide glyphosate, allowing farmers to apply the herbicide to kill weeds without harming the crop.
- The production of genetically identical organisms through asexual reproduction is known as:
a) Hybridization
b) Cross-breeding
c) Cloning
d) Transgenesis
Answer: c) Cloning
Explanation:
Cloning is the process of creating genetically identical copies of an organism through asexual reproduction, often using techniques like somatic cell nuclear transfer.
- Which of the following techniques can be used to analyze gene expression by measuring mRNA levels?
a) Southern blotting
b) Northern blotting
c) Western blotting
d) PCR
Answer: b) Northern blotting
Explanation:
Northern blotting is used to detect and measure mRNA levels, providing insights into gene expression patterns. It involves separating RNA by electrophoresis and probing with a complementary RNA or DNA sequence.
- In genetic engineering, what is the purpose of a vector?
a) To break down proteins
b) To amplify DNA
c) To carry foreign genes into a host cell
d) To degrade RNA
Answer: c) To carry foreign genes into a host cell
Explanation:
A vector, such as a plasmid or virus, is used in genetic engineering to deliver foreign DNA into a host cell where it can be expressed or replicated.
- Which of the following is commonly used as a vector in animal gene therapy?
a) Ti plasmid
b) Bacteriophage
c) Retrovirus
d) RNA polymerase
Answer: c) Retrovirus
Explanation:
Retroviruses are commonly used as vectors in animal gene therapy because they can integrate their genetic material into the host cell’s genome, making them useful for stable, long-term expression of therapeutic genes.
- RNA interference (RNAi) technology can be used to:
a) Increase the expression of a gene
b) Silence or reduce the expression of a gene
c) Amplify DNA
d) Mutate a gene
Answer: b) Silence or reduce the expression of a gene
Explanation:
RNA interference (RNAi) is a method used to silence or reduce the expression of specific genes by degrading the mRNA, thus preventing the production of the corresponding protein.
- Which of the following is NOT true about genetically modified organisms (GMOs)?
a) They can be used to improve crop yields.
b) They are always beneficial to the environment.
c) They can be engineered for pest resistance.
d) They can reduce the need for chemical pesticides.
Answer: b) They are always beneficial to the environment.
Explanation:
While GMOs can have benefits like improving crop yields and reducing pesticide use, they are not always beneficial to the environment. There are concerns about unintended ecological effects, such as gene flow to wild species.
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